OK, let's work through this together. We're starting with 403 and we're going to multiply it by 20, which means we add 403 to itself 20 times.
Step 1: 0 + 403 = 403
Step 2: 403 + 403 = 806
Step 3: 806 + 403 = 1209
Step 4: 1209 + 403 = 1612
Step 5: 1612 + 403 = 2015
Step 6: 2015 + 403 = 2418
Step 7: 2418 + 403 = 2821
Step 8: 2821 + 403 = 3224
Step 9: 3224 + 403 = 3627
Step 10: 3627 + 403 = 4030
Step 11: 4030 + 403 = 4433
Step 12: 4433 + 403 = 4836
Step 13: 4836 + 403 = 5239
Step 14: 5239 + 403 = 5642
Step 15: 5642 + 403 = 6045
Step 16: 6045 + 403 = 6448
Step 17: 6448 + 403 = 6851
Step 18: 6851 + 403 = 7254
Step 19: 7254 + 403 = 7657
Step 20: 7657 + 403 = 8060

So, 403*20 = 8060